Scattering of surface acoustic waves by a phononic crystal revealed by heterodyne interferometry

Surface acoustic wave propagation within a two-dimensional phononic band gapstructure has been studied using a heterodyne laser interferometer.Acoustic waves are launched by interdigital transducers towards a square lattice of holes etched in a piezoelectric medium. Interferometer measurements performed at frequencies lying below, within, and above the expected band gap frequency range provide direct information of the wave interaction with the phononic crystal, revealing anisotropic scattering into higher diffraction orders depending on the apparent grating pitch at the boundary between the phononic crystal and free surface. Furthermore, the measurements also confirm the existence of an elastic band gap, in accordance with previous electrical measurements and theoretical predictions.Peer reviewe

Phase sensitive absolute amplitude detection of surface vibrations using homodyne interferometry without active stabilization

A detection scheme for obtaining phase and absolute amplitude information of surface vibrations on microacoustic components using homodyne laser interferometry is described. The scheme does not require active stabilization of the optical path length of the interferometer. The detection setup is realized in a homodyneMichelson interferometer configuration, and selected measurements on a 374 MHz surface acoustic wave fan-shaped filter and two different piezoelectrically actuated micromechanical resonators are presented to demonstrate the performance of the instrument. With the current detection electronics, the interferometer is capable of detecting out-of-plane surface vibrations up to 2 GHz with a lateral resolution of better than 1 μm and with a minimum detectable vibration amplitude of ∼1 pm.Peer reviewe

An Approach to Solid Phase Identification in a Ca-S-O System by Quantitative Energy Dispersive X-Ray Microanalysis

Solid phases formed in the limestone sulphation reaction were identified by scanning electron microscopy with backscattered electron (BSE) imaging and by quantitative energy dispersive X-ray (EDX) microanalysis of calcium and sulphur. Since calcium and sulphur can form several compounds in the Ca-S-O system, two quantities, the sum of oxides (CaO+SO3) and the molar ratio (CaO/SO3), were used to calculate empirical formulae for the compounds actually present. A method for analysing the experimental results is proposed, the mathematical expressions employed are presented and the numerical coefficients tabulated. It is shown with some examples that the method used here provides useful criteria for the identification of limestone sulphation products

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Characterization of energy trapping in a bulk acoustic wave resonator

Acoustic wave fields both within the active electrode area of a solidly mounted 1.8 GHz bulk acoustic waveresonator, and around it in the surrounding region, are measured using a heterodyne laser interferometer. Plate-wave dispersion diagrams for both regions are extracted from the measurement data. The experimental dispersion data reveal the cutoff frequencies of the acoustic vibration modes in the region surrounding the resonator, and, therefore, the energy trapping range of the resonator can readily be determined. The measureddispersionproperties of the surrounding region, together with the abruptly diminishing amplitude of the dispersion curves in the resonator, signal the onset of acoustic leakage from the resonator. This information is important for verifying and further developing the simulation tools used for the design of the resonators. Experimental wave field images, dispersion diagrams for both regions, and the threshold for energy leakage are discussed.Peer reviewe

Material anisotropy unveiled by random scattering of surface acoustic waves

We consider launching a monochromatic surface acoustic wave packet on a large set of random scatterers. The interference of the multiple scatteredwaves creates a random pattern of ripples on the crystal surface that is recorded by optical interferometry. The Fourier transform of the amplitude and phase data of the measured wave field unveils the complete slowness curve, i.e., the wave-vector as a function of the propagation angle. A simple acoustic speckle model is proposed to explain this observation.Peer reviewe

Effect of incremental amounts of camelina oil on milk fatty acid composition in lactating cows fed diets based on a mixture of grass and red clover silage and concentrates containing camelina expeller

Camelina is an ancient oilseed crop that produces an oil rich in cis-9,cis-12 18:2 (linoleic acid, LA) and cis9,cis-12, cis-15 18:3 (alpha-linolenic acid, ALA); however, reports on the use of camelina oil (CO) for ruminants are limited. The present study investigated the effects of incremental CO supplementation on animal performance, milk fatty acid (FA) composition, and milk sensory quality. Eight Finnish Ayrshire cows (91 d in milk) were used in replicated 4 x 4 Latin squares with 21-d periods. Treatments comprised 4 concentrates (12 kg/d on an air-dry basis) based on cereals and camelina expeller containing 0 (control), 2, 4, or 6% CO on an air-dry basis. Cows were offered a mixture of grass and red clover silage (RCS; 1:1 on a dry matter basis) ad libitum. Incremental CO supplementation linearly decreased silage and total dry matter intake, and linearly increased LA, ALA, and total FA intake. Treatments had no effect on whole-tract apparent organic matter or fiber digestibility and did not have a major influence on rumen fermentation. Supplements of CO quadratically decreased daily milk and lactose yields and linearly decreased milk protein yield and milk taste panel score from 4.2 to 3.6 [on a scale of 1 (poor) to 5 (excellent)], without altering milk fat yield. Inclusion of CO linearly decreased the proportions of saturated FA synthesized de novo (4:0 to 16:0), without altering milk fat 18:0, cis-9 18:1, LA, and ALA concentrations. Milk fat 18:0 was low (Peer reviewe

Heterozygous frameshift mutation in keratin 5 in a family with Galli-Galli disease

BACKGROUND: Reticulate pigmentary disorders include the rare autosomal dominant Galli–Galli disease (GGD) and Dowling–Degos disease (DDD). Clinical diagnosis between some of the subtypes can be difficult due to a degree of overlap between clinical features, therefore analysis at the molecular level may be necessary to confirm the diagnosis. OBJECTIVES: To identify the underlying genetic defect in a 48-year-old Asian-American woman with a clinical diagnosis of GGD. METHODS: Histological analysis was performed on a skin biopsy using haematoxylin–eosin staining. KRT5 (the gene encoding keratin 5) was amplified from genomic DNA and directly sequenced. RESULTS: The patient had a history of pruritus and hyperpigmented erythematous macules and thin papules along the flexor surfaces of her arms, her upper back and neck, axillae and inframammary areas. Hypopigmented macules were seen among the hyperpigmentation. A heterozygous 1-bp insertion mutation in KRT5 (c.38dupG; p.Ser14GlnfsTer3) was identified in the proband. This mutation occurs within the head domain of the keratin 5 protein leading to a frameshift and premature stop codon. CONCLUSIONS: From the histological findings and mutation analysis the individual was identified as having GGD due to haploinsufficiency of keratin 5

Extraction of lateral eigenmode properties in thin film bulk acoustic wave resonator from interferometric measurements

A heterodyne laser interferometer is used to study acoustic wave fields excited in a 1.8 GHz AlN thin film bulk acoustic waveresonator. The electrical response of the resonator exhibits a strong thickness resonance onto which spurious modes, caused by lateral standing plate waves, are superposed. Optical interferometermeasurements are used to extract dispersion curves of the laterally propagating waves responsible for the spurious responses. A discrete eigenmode spectrum due to the finite lateral dimensions of the resonator is observed. An equivalent circuit model for a multimode resonator is fitted to the mechanical resonator response extracted along a single curve in the dispersion diagram, and is used to determine properties, such as Q-values, of the individual lateral eigenmodes.Measuredwave field images, extracted dispersion curves, and the eigenmode spectrum with the model fitting results are presented.Peer reviewe

Aerosols, Clusters, Greenhouse Gases, Trace Gases and Boundary-Layer Dynamics : on Feedbacks and Interactions

Turbulence is the key process transporting material and energy in the atmosphere. Furthermore, turbulence causes concentration fluctuations, influencing different atmospheric processes such as deposition, chemical reactions, formation of low-volatile vapours, formation of new aerosol particles and their growth in the atmosphere, and the effect of aerosol particles on boundary-layer meteorology. In order to analyse the connections, interactions and feedbacks relating those different processes require a deep understanding of atmospheric turbulence mechanisms, atmospheric chemistry and aerosol dynamics. All these processes will further influence air pollution and climate. The better we understand these processes and their interactions and associated feedback, the more effectively we can mitigate air pollution as well as mitigate climate forcers and adapt to climate change. We present several aspects on the importance of turbulence including how turbulence is crucial for atmospheric phenomena and feedbacks in different environments. Furthermore, we discuss how boundary-layer dynamics links to aerosols and air pollution. Here, we present also a roadmap from deep understanding to practical solutions.Peer reviewe